MEAT QUALITY PARAMETERS Dr. Rio Olympias Sujarwanta, S.Pt., M.Sc.

Specific Parameter for Meat Quality Meat color, Water holding capacity by meat protein, Meat pH, Cooking loss, Tenderness and texture, Flavor and smell

Meat Color The factors affecting meat color are: feeding, species, breeds, age, sex, muscle activity, pH, and oxygen. Meat pigment consists of myoglobin, chromoprotein, and hemoglobin Different meat colors are caused by different concentrations of myoglobin, chemical state of myoglobin (myoglobin, oxymyoglobin, metmyoglobin), and chemical and physical state of other components in meat.

Meat Color Myoglobin is sarcoplasmic protein of single polypeptide chains bound in the surrounding of heme group which bring oxygen. The amount of myoglobin in veal is 1-3 mg/g, in beef 4-10 mg/g, and in older beef 16-20 mg/g. Myoglobin undergoes changes in PSE meat, caused by a very rapid decrease in postmortem pH. The concentration of myoglobin increases with age so that older animals have darker color.

Meat Color Muscle differences cause meat color differences because each muscle has different activities, resulting in different supply of O2. Different colors of meat surface are caused by chemical state of myoglobin, i.e. bright red (oxymyoglobin), brown (metmyoglobin). Temperature affects cooked-meat color, i.e. meat which is cooked at the temperature of 60oC has bright red color, and at 70-80oC has grayish brown color. Myoglobin undergoes denaturation at the heating temperature of 80-85oC.

Assessment of Meat Color

Water Holding Capacity Water-holding capacity (WHC) is the ability of meat protein to hold its water or added water due to external pressure effect such as centrifugation. There are three compartments (forms) of water bound in meat, namely: water bound chemically by protein (4-5%), water bound weakly by protein (4%) and bulk (free) water among protein molecules (10%). A decrease in WHC can be seen through fluid exudation called weep in unfrozen raw meat; or drip in frozen meat which is thawed, folds in cooked meat.

Water Holding Capacity WHC is affected by pH. It decreases from pH 7-10 until the isoelectric pH of meat protein 5,0-5,1, then increases until below the isoelectric point of meat protein. Aging increases WHC due to the change in water-protein relation. Cooking can result in a change in WHC due to the presence of meat protein solubility and denaturation. Heating can decrease WHC due to a decrease in acidic group that results in an increased pH leading to a change in the isoelectric point of meat protein.

Water Holding Capacity Different WHC is also found among muscles and muscle locations of the same muscle due to different amount of lactic acids which affect pH. WHC is also related to marbling, i.e. marbling will loosen the microstructure of meat and give more opportunity for meat protein to bind water.

Assessment of Water Holding Capacity WHC can be assessed by using several methods including press method (Hamm, 1972), Centrifugation method with a very rapid velocity (Bouton et al., 1971). Assessment with Hamm Method 300 mg meat sample is put on water-free filter paper between 2 glass plates, then it is subjected to 35 kg/cm2 pressure for 5 minutes.

Assessment of Water Holding Capacity The area of water subtracted with the area of sample is the water released from the press process. Total water content (KAT) is measured with AOAC (1980) Water Holding Capacity (%) = KAT (%) – KAB (separated water content) (%)

Assessment of Water Holding Capacity The area of water subtracted with the area of sample is the water released from the press process. Total water content (KAT) is measured with AOAC (1980) Water Holding Capacity (%) = KAT (%) – KAB (separated water content) (%)

Result of WHC assessment with Hamm method

Meat pH Ultimate pH of meat is meat pH after undergoing postmortem glycolysis. Meat pH is related to water holding capacity, cooking loss, and tenderness. Meat pH decreases after the slaughter of animals. Decrease in pH is caused by the occurrence of anaerobic postmortem glycolysis which produces lactic acids. The more glycogen supply stored during slaughter, the lower ultimate pH of meat.

Meat pH Meat pH is related to WHC, meat juice, tenderness, cooking loss, i.e. an increase in pH will increase meat juice and WHC, but decrease cooking loss. Factors affecting ultimate meat pH Pre-slaughter factors: age, species, breeds, types of animals, resting, slaughter method, type of muscle, muscle location, muscle glycogen supply. Post-slaughter factors: electrical stimulation, chilling, aging, storage, and cooking.

Measurement of meat pH Meat pH is measured with pH meter electrode. Meat is finely ground, then added with H2O with a ratio of 1:9 The meat is homogenized, then its pH is measured with pH meter which has been calibrated with pH 7 and 4 buffer. Cooking and meat pH Cooking can increase the value of meat pH because it leads to acidic group loss (amino acids).

Cooking Loss Cooking loss is the loss of meat weight or mass due to cooking process. Cooking loss is a function of temperature and duration of cooking. The loss of mass consists of water and other water-soluble components namely: protein, vitamin, and mineral. Meat with lower cooking loss has better quality compared to that with higher cooking loss because the loss of nutrients during cooking is higher. The value of meat cooking loss is around 1,5 – 54%, with the average of 15 - 40%.

Factors affecting cooking loss Intrinsic: age, species, breed, sex, type of animal, type of muscle, muscle location, length of sarcomere, marbling fats. Extrinsic: temperature, duration of cooking, Cooking loss increases due to an increase in the temperature and duration of cooking. Cooking loss decreases, linearly, as the animal age increases. Marbling fats will inhibit the release of meat juice during cooking, although meat with more marbling will lose more fats.

Measurement of Cooking Loss Meat is cut in cuboid shape with the size of length x width x thickness (5x3x2) cm and measured in scale. Sample is put in a plastic and vacuumed. Sample is heated at the temperature of 80oC for 60 minutes. Sample is chilled and measured in scale.

Tenderness and Texture Myofibril structure and contraction status. The composition of connective tissues and the level of its cross-ties. Water holding capacity by meat protein and meat juice. The texture of meat is the size of muscle fiber bundles surrounded by perimysium of connective tissues dividing muscle longitudinally.

Tenderness and Texture The texture of muscle is categorized into two groups: coarse texture (large size of muscle fiber bundles), and soft texture (small size of muscle fiber bundles). Fiber bundle is determined by the amount of the fiber, size of fiber, and the number of perimysium surrounding the muscle fiber bundles. Tenderness includes 3 aspects: (1) the ease of penetration of the meat by the teeth, (2) the ease with which the meat breaks into smaller fragments, and (3) the amount of residue remaining after chewing.

Tenderness and Texture Tenderness is affected by connective tissues in meat (epimysium, perimysium and endomysium). Generally, the older the animal, the lower the tenderness because of denser and thus stronger connective tissues. The types of muscle also influence the level of meat tenderness due to different physiological functions of muscle. Cooking also affects tenderness; it can either increase or decrease the tenderness level according to the duration and temperature of cooking. Duration of cooking affects collagen softening, while cooking temperature affects myofibrillar toughness.

Meat Tendering Enzymes Enzymes from plant: papain (papaya), bromelain (nanas), and ficin (ficus). Meat tenderizing enzymes can be injected right before the animal is slaughtered. Enzyme solution can also be used on meat cuts by soaking, sprinkle, smearing, and injection. Meat tenderizing can also be done by injecting sodium salt (NaCl, STPP, lactic Na).  

Flavor and Smell Factors affecting meat flavor are: feeding, age, species, breeds, sex, fats, duration and condition of storage after slaughter, and cooking method, duration, and temperature. The smell and flavor of cooked meat are determined by water and fat-soluble precursors, and volatile substance of meat The flavor and smell of meat are determined by the composition of fatty acids composing the meat fats, especially marbling fats. The oxidation of fatty acids will form carbonyl compound which will cause undesirable flavor and smell of meat .  

Assessment of Flavor and Smell Flavor and smell are tested by panel taste based on the palatability or preference level.   Panelists Panel is one person or a group of people having the duty of scoring the characteristics or quality of something in a subjective method. Food assessment by panellists is based on the subjective evaluation of the panellists with certain sensory procedure to abide by.

Types of Panelists Individual expert Small expert panel Trained panel Untrained panel Semi-trained panel Consumer panel

Important elements in organoleptic testing laboratory Atmosphere: including the state of being clean, tranquil, tidy, orderly, and aesthetic. Space: including a room for sample preparation/kitchen, a room for tasting, waiting room for panel, and meeting room for panel. Infrastructure and facilities: including equipment for sample preparation, serving equipment of sample and communication equipment

Requirements of organoleptic testing laboratory Isolation: in order to be tranquil, laboratory must be separated from other rooms or activities, the waiting room must be made relaxing, and each panel should have a separate tasting room Sound proof: tasting room should be made sound proof, laboratory should be built far from crowd Level of smell: tasting room should be made free from any smell (perfume / cigarette), far from sewage and processing room. Temperature and humidity: the temperature of the room should be made constant at room temperature (20-25oC) and the humidity around 60%. Lighting: the lighting in the room should not be made too bright or too dim.

Methods of organoleptic testing Different test Preference test/acceptance test) Scalar test Description test Different test and preference test: frequently used in analysis of process and assessment of end products (outcomes). Scalar and description test: frequently used in quality control. Variables of meat sensory Look (color, texture, juiciness) Taste (tenderness, flavor, smell)

References Aberle, E.D., J.C. Forrest, D.E. Gerrard, E.W. Mills, H.B. Hedrick, M.D. Judge, R.A. Merkel, 2001. Principles of Meat Science. 4th ed. Kendall/Hunt Publishing Company, Dubuque, Iowa. Swatland, H.J., 1984. Structure and Development of Meat Animals. Prentice-Hall, Inc., Englewood Cliffs, New Jersey. Soeparno, 2015. Ilmu dan Teknologi Daging. Cetakan ke-6 (Edisi Revisi). Gadjah Mada University Press, Yogyakarta. Soeparno, 2011. Ilmu Nutrisi dan Gizi Daging. Cetakan pertama. Gadjah Mada University Press, Yogyakarta.

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